For the base:
6 oz (175 g) plain chocolate oatmeal biscuits (Digestives??)
2 oz (50 g) butter, melted
For the cheesecake:
5 oz (150 g) dark chocolate (75 per cent cocoa solids), broken into small pieces
12 oz (350 g) ricotta, at room temperature
1 x 200 ml tub half-fat crème fraîche, at room temperature
2 large eggs, separated
2 oz (50 g) golden caster sugar
3 leaves gelatine
2 tablespoons milk
For the chocolate curls:
1 x 100 g bar dark chocolate (75 per cent cocoa solids), broken into small pieces
a dusting of cocoa powder, to finish
METHOD place the biscuits in a plastic food bag and crush them, using a rolling pin. Then tip the crumbs into a mixing bowl. Now add the melted butter to bind it all together, then press the mixture into the base of the tin, pop it into the oven and bake for 10 minutes. After that, remove it and leave it to cool.
Meanwhile, melt 5 oz (150 g) chocolate in a heatproof bowl over a pan of barely simmering water, making sure the bowl doesn’t touch the water, then remove it from the heat and let it cool as well.
Next, in a large mixing bowl, whisk together the ricotta, crème fraîche, egg yolks and sugar until smooth and well blended. Now soak the leaves of gelatine in a small bowl of cold water for about 5 minutes, and while that’s happening heat the milk in a small saucepan up to simmering point before taking it off the heat.
Squeeze the excess water from the gelatine, then add it to the milk and whisk until it has dissolved. Now stir the gelatine and milk along with the cooled chocolate into the ricotta mixture, until it is all thoroughly blended.
Now, in another bowl and using clean beaters, whisk the egg whites to the soft-peak stage. Then first fold a tablespoon of egg white into the cheesecake mixture to loosen it, and then carefully but thoroughly fold in the rest of the egg white. Next pour the mixture on to the prepared base, cover with clingfilm and chill in the fridge for at least 4 hours (even overnight – the longer the better).
For the chocolate curls, melt the chocolate as before, then pour it on to the base of the plate to form an even layer about ¼ inch (5 mm) thick and place the plate into the fridge to chill and set for 45 minutes (the chocolate should be hard enough that if you press the surface it shouldn’t leave an indentation – but without being rock hard).
Then, using either a large-bladed knife held with both hands or a cheese slice, pull the blade across the chocolate, pressing down slightly. As the blade comes towards you the chocolate will form curls (if the chocolate is too hard, it will be brittle and will break rather than forming curls, in which case leave at room temperature for 5 minutes before trying again).
Store the chocolate curls in a sealed container in the fridge until you need them.
You probably won’t need all this chocolate to make enough curls to top the cake, but as the layer of chocolate gets thinner it will be harder to form nice curls, and the remaining chocolate can be lifted off the plate and re-melted for another recipe (or simply eaten!).
To serve the cheesecake, carefully remove it from the tin onto a serving plate, decorate with the chocolate curls and give them a light dusting of sieved cocoa powder.